Covered electrical wire, terminal-equipped electrical wire, copper alloy wire, and copper alloy stranded wire

ABSTRACT

A covered electrical wire comprising a conductor and an insulating covering layer provided outside the conductor, the conductor being a stranded wire composed of a strand of a plurality of copper alloy wires: composed of a copper alloy containing Fe in an amount of 0.1% by mass or more and 1.6% by mass or less, P in an amount of 0.05% by mass or more and 0.7% by mass or less, and Sn in an amount of 0.05% by mass or more and 0.7% by mass or less, with the balance being Cu and impurities; and having a wire diameter of 0.5 mm or less, the copper alloy wire having a tensile strength of 385 MPa or more and a work-hardening exponent of 0.1 or more.

The present application claims priority based on Japanese PatentApplication No. 2016-217040 dated Nov. 7, 2016 and InternationalApplication PCT/JP2016/089161 dated Dec. 28, 2016, and incorporates allthe contents described in the above Japanese and InternationalApplications.

TECHNICAL FIELD

The present invention relates to a covered electrical wire, aterminal-equipped electrical wire, a copper alloy wire, and a copperalloy stranded wire.

BACKGROUND ART

Conventionally, a wire harness composed of a plurality ofterminal-equipped electrical wires bundled together is used for a wiringstructure of an automobile, an industrial robot or the like. Anelectrical wire equipped with a terminal is an electrical wire having anend covered with an insulating cover layer, through which a conductor isexposed and a terminal such as a crimp terminal is attached to theconductor. Typically, each terminal is inserted into one of terminalholes provided in a connector housing, and is mechanically connected tothe connector housing. The electrical wire is connected to the body of adevice via the connector housing. Such connector housings may beconnected to each other to thus connect electrical wires to each other.Copper or a similar, copper-based material is mainly used as aconstituent material of the conductor (for example, see PatentLiterature 1).

CITATION LIST Patent Literature

-   -   PTL 1: Japanese Patent Laying-Open No. 2014-156617

SUMMARY OF INVENTION

According to the present disclosure, a covered electrical wire is

-   -   a covered electrical wire comprising a conductor and an        insulating covering layer provided outside the conductor,    -   the conductor being a stranded wire composed of a strand of a        plurality of copper alloy wires:    -   composed of a copper alloy containing        -   Fe in an amount of 0.1% by mass or more and 1.6% by mass or            less,        -   P in an amount of 0.05% by mass or more and 0.7% by mass or            less, and        -   Sn in an amount of 0.05% by mass or more and 0.7% by mass or            less,        -   with the balance being Cu and impurities; and    -   having a wire diameter of 0.5 mm or less,    -   the copper alloy wire having a tensile strength of 385 MPa or        more and a work-hardening exponent of 0.1 or more.

According to the present disclosure, a terminal-equipped electrical wirecomprises:

-   -   the covered electrical wire according the present disclosure;        and a terminal attached to an end of the covered electrical        wire.

According to the present disclosure, a copper alloy wire is

-   -   a copper alloy wire used for a conductor, the copper alloy wire:    -   being composed of a copper alloy containing        -   Fe in an amount of 0.1% by mass or more and 1.6% by mass or            less,        -   P in an amount of 0.05% by mass or more and 0.7% by mass or            less, and        -   Sn in an amount of 0.05% by mass or more and 0.7% by mass or            less,        -   with the balance being Cu and impurities; and    -   having a wire diameter of 0.5 mm or less,    -   a tensile strength of 385 MPa or more, and    -   a work hardening exponent of 0.1 or more.

According to the present disclosure, a copper alloy stranded wire isformed of a strand of a plurality of copper alloy wires each accordingto the present disclosure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic perspective view showing a covered electrical wireaccording to an embodiment.

FIG. 2 is a schematic side view showing a vicinity of a terminal of aterminal-equipped electrical wire according to an embodiment.

FIG. 3 is a transverse cross-sectional view of the FIG. 2terminal-equipped electrical wire taken along a line (III)-(III).

FIG. 4 illustrates a method for measuring “impact resistance energy in astate with a terminal attached” as measured in Test Examples 1 and 2.

DETAILED DESCRIPTION

[Problem to be Solved by the Present Disclosure]

There is a demand for an electrical wire which is excellently conductiveand excellent in strength and also excellent in impact resistance. Inparticular, there is a demand for an electrical wire which is hard tobreak against impact even when the electrical wire has a conductorcomposed of a thin wire member.

In recent years, as automobiles are increasingly enhanced in performanceand function, more electric devices and control devices of a variety oftypes are mounted on the automobiles, and accordingly, more electricalwires tend to be used for these devices. This also tends to increase theelectrical wires in weight. On the other hand, for preservation ofenvironment, it is desirable to reduce electrical wires in weight forthe purpose of improving fuel economy of automobiles. Although a wiremember composed of a copper-based material as described above easily hashigh conductivity, it easily has a large weight. For example, if a thincopper based wire member having a wire diameter of 0.5 mm or less isused for a conductor, it is expected to achieve high strength throughwork hardening, and weight reduction by small diameter. However, such athin wire member as described above has a small cross section, and whenit receives an impact, it tends to do so with small force andaccordingly, it is easily broken when it receives an impact.Accordingly, there is a demand for a copper based wire member which isexcellent in impact resistance even when it is thin as described above.

An electrical wire used with a terminal such as a crimp terminalattached thereto as described above has its conductor compressed at aterminal attachment portion, which has a cross section smaller in areathan that of the remaining portion of the conductor (hereinafter alsoreferred to as the main wire portion). Accordingly, the terminalattachment portion of the conductor tends to be a portion easily brokenwhen it receives an impact. Therefore, there is a demand for even such athin copper-based wire member described above to have a terminalattachment portion and a vicinity thereof not easily broken when itreceives an impact, that is, to be also excellent in impact resistancein a state with a terminal attached thereto.

Furthermore, when electrical wires applied to automobiles or the likeare routed therein or connected to a connector housing, they may bepulled, bent or twisted, or they may receive vibration in use.Electrical wires applied to robots or the like may be bent or twisted inuse. An electrical wire which is not easily broken when repeatedly bentor twisted and thus has excellent fatigue resistance, and an electricalwire which excellently fixes a terminal such as a crimp terminal, asdescribed above, are more preferable.

Accordingly, it is an object to provide a covered electrical wire, aterminal-equipped electrical wire, a copper alloy wire, and a copperalloy stranded wire which are excellently conductive and excellent instrength, and in addition, also excellent in impact resistance.

[Advantageous Effect of the Present Disclosure]

The presently disclosed covered electrical wire, terminal-equippedelectrical wire, copper alloy wire, and copper alloy stranded wire areexcellently conductive and excellent in strength, and in addition, alsoexcellent in impact resistance.

DESCRIPTION OF EMBODIMENTS

Initially, embodiments of the present invention will be enumerated anddescribed.

(1) A covered electrical wire according to one aspect of the presentdisclosure is

-   -   a covered electrical wire comprising a conductor and an        insulating covering layer provided outside the conductor,    -   the conductor being a stranded wire composed of a strand of a        plurality of copper alloy wires:    -   composed of a copper alloy containing        -   Fe in an amount of 0.1% by mass or more and 1.6% by mass or            less,        -   P in an amount of 0.05% by mass or more and 0.7% by mass or            less, and        -   Sn in an amount of 0.05% by mass or more and 0.7% by mass or            less,        -   with the balance being Cu and impurities; and    -   having a wire diameter of 0.5 mm or less,    -   the copper alloy wire having a tensile strength of 385 MPa or        more and a work-hardening exponent of 0.1 or more.

The above-described stranded wire includes a plurality of copper alloywires simply stranded together and in addition, such wires strandedtogether and subsequently compressed and thus formed, i.e., a so-calledcompressed stranded wire. This also applies to a copper alloy strandedwire of item (11) described later. A typical stranding method isconcentric stranding.

When the copper alloy wire is a round wire its diameter is defined as awire diameter, whereas when the copper alloy wire has a transverse crosssection other than a circle, the diameter of a circle having an areaequivalent to that of the transverse cross section is defined as a wirediameter.

Since the covered electrical wire described above comprises a wiremember composed of a copper based material and having a small diameterfor a conductor, the covered electrical wire is excellently conductiveand excellent in strength, and in addition, light in weight. Since thiscopper alloy wire is composed of a copper alloy having a specificcomposition including Fe, P and Sn in a specific range, theabove-described covered electrical wire is further excellentlyconductive and further excellent in strength and in addition, alsoexcellent in impact resistance, as will be described below. In thecopper alloy described above, Fe and P are typically present in a matrixphase (Cu) as precipitates and crystallites containing Fe and P such asFe₂P or a similar compound, and the elements effectively enhancestrength through enhanced precipitation and effectively maintain highconductivity by reduction of solid solution in Cu. Further, Sn isincluded in a specific range, and enhanced solid solution of Sn furtherenhances strength effectively. The above described enhancedprecipitation and enhanced solid solution provide high strength, andeven when a heat treatment is performed to increase elongation or thelike, the copper alloy wire has strength as high as 385 MPa or more, andalso has high toughness and is thus also excellent in impact resistance.By appropriately adjusting a heat treatment condition in a manufacturingprocess, as will be described hereinafter, while a conductivity as highas 60% IACS or more and strength as high as 385 MPa or more areprovided, excellent impact resistance is also provided. Such a coveredelectrical wire as described above, a copper alloy stranded wireconstituting a conductor of the covered electrical wire, and a copperalloy wire serving as each elemental wire forming the copper alloystranded wire can be said to have high conductivity, high strength andhigh toughness in a good balance.

In addition, the covered electrical wire also has excellent fatigueresistance as the covered electrical wire comprises a conductor mainlycomposed of a high strength copper alloy wire having a tensile strengthof 385 MPa or more. In particular, when the covered electrical wirecomprising as a conductor a strand of copper alloy wires having highstrength and also having high toughness, as has been described above, iscompared with an electrical wire comprising a solid wire of the samecross section as a conductor, the former's conductor (or strand) as awhole tends to be better in mechanical properties such as bendabilityand twistability and is thus more excellent in fatigue resistance.

Furthermore, the above stranded wire and copper alloy wire have awork-hardening exponent as large as 0.1 or more, so that when the wiresare subjected to plastic-working, such as compression-working,accompanied by reduction in cross section, they are work-hardened tohave a plastically worked portion enhanced in strength. Note that thecovered electrical wire comprises a copper alloy wire per se having highstrength, as described above, so that when it has a terminal such as acrimp terminal fixed thereto, the former fixes the latter with largeforce (see Test Example 1 described hereinafter). In addition, the highwork-hardening exponent as described above allows work-hardening toenhance the conductor (or strand) at the terminal-connected portion instrength and thus allows the terminal to be further firmly fixed. Such acovered electrical wire as described above has a larger force to fix theterminal and thus further excellently fixes the terminal, and when thecovered electrical wire receives an impact, the covered electrical wirehas the terminal-connected portion hard to break and thus also has anexcellent impact resistance in the state with the terminal attached.

(2) As an example of the covered electrical wire,

-   -   the copper alloy includes an embodiment containing one or more        elements selected from C, Si, and Mn in an amount of 10 ppm or        more and 500 ppm or less by mass in total.

C, Si, and Mn contained in a specific range functions as a deoxidizingagent for elements such as Fe, P, Sn, and the like to prevent/reduceoxidation of these elements to effectively, appropriately obtain highconductivity and high strength attributed to containing these elements.Furthermore, the above embodiment is also excellently conductive as itcan suppress reduction in conductivity attributed to excessivelycontaining C, Si, and Mn. Thus, the above-described embodiment isfurther excellently conductive and further excellent in strength.

(3) An example of the covered electrical wire described above is

-   -   an embodiment in which the copper alloy wire provides an        elongation at break of 5% or more.

The above embodiment comprises a copper alloy wire having a largeelongation at break as a conductor, and is thus excellent in impactresistance, and in addition, also hard to break even when bent ortwisted, and thus also excellent in bendability and twistability.

(4) An example of the covered electrical wire described above includes

-   -   an embodiment in which the copper alloy wire has a conductivity        of 60% IACS or more and a tensile strength of 400 MPa or more.

The above embodiment comprises a copper alloy wire having highconductivity and higher tensile strength as a conductor, and is thusexcellently conductive and excellent in strength.

(5) An example of the covered electrical wire includes

-   -   an embodiment providing a terminal fixing force of 45 N or more.

How terminal fixing force, impact resistance energy in a state with aterminal attached, as will described hereinafter at items (6) and (12),and impact resistance energy, as will be described hereinafter at items(7) and (13), are measured will be described hereinafter (see TestExamples 1 and 2).

In the above embodiment, when a terminal such as a crimp terminal isattached, the terminal can be fixed firmly and hence excellently. Thusthe above-described embodiment is excellently conductive and excellentin strength, and in addition, also excellent in impact resistance, andalso presents excellent performance in fixing the terminal, and can thusbe suitably used for the above-described terminal-equipped electricalwire and the like.

(6) An example of the above-described covered electrical wire includes

-   -   an embodiment in which an impact resistance energy in a state        with the terminal attached is 3 J/m or more.

The above embodiment provides large impact resistance energy in a statewith a terminal such as a crimp terminal attached, and it is hard tobreak at the terminal attachment portion even when receiving an impactin the state with the terminal attached. Thus the above-describedembodiment is excellently conductive and excellent in strength, andexcellent in impact resistance, and also has an excellent impactresistance in a state with a terminal attached thereto, and can besuitably used for the above-described terminal-equipped electrical wireand the like.

(7) An example of the covered electrical wire described above includes

-   -   an embodiment in which the covered electrical wire alone        provides an impact resistance energy of 6 J/m or more.

In the above embodiment, the covered electrical wire per se has highimpact resistance energy, and even when it receives an impact, it ishard to break, and thus excellent in impact resistance.

(8) An example of the covered electrical wire described above includes

-   -   an embodiment in which the copper alloy has a mass ratio of Fe/P        of 4.0 or more.

The above embodiment contains Fe in a large amount relative to P, and itis easy to form a compound without excess or deficiency of Fe and P andit is thus possible to effectively prevent solid solution of excessive Pin the matrix phase, and hence reduced conductivity. In this regard theabove embodiment further easily maintains high conductivity of Cu andhence easily has higher conductivity.

(9) A terminal equipped electrical wire in one aspect of the presentdisclosure comprises:

-   -   the covered electrical wire according to any one of the above        items (1) to (8);        and a terminal attached to an end of the covered electrical        wire.

Since the above-described terminal-equipped electrical wire includes thecovered electrical wire as described above, it is excellently conductiveand excellent in strength, and in addition, also excellent in impactresistance, as has been described above. In addition, since theabove-described terminal-equipped electrical wire includes the coveredelectrical wire as described above, it also has excellent fatigueresistance, excellently fixes the terminal, and has excellent impactresistance in a state with the terminal attached thereto, as has beendescribed above.

(10) A copper alloy wire according to one aspect of the presentdisclosure is

-   -   a copper alloy wire used for a conductor, the copper alloy wire:    -   being composed of a copper alloy containing        -   Fe in an amount of 0.1% by mass or more and 1.6% by mass or            less,        -   P in an amount of 0.05% by mass or more and 0.7% by mass or            less, and        -   Sn in an amount of 0.05% by mass or more and 0.7% by mass or            less,        -   with the balance being Cu and impurities; and    -   having a wire diameter of 0.5 mm or less,    -   a tensile strength of 385 MPa or more, and    -   a work hardening exponent of 0.1 or more.

The above-described copper alloy wire is a thin wire member composed ofa copper-based material, and when it is used as a conductor for anelectrical wire or the like in the form of a solid wire or a strandedwire, it is excellently conductive and excellent in strength, and inaddition, contributes to weight reduction of the electrical wire. Inparticular, the above-described copper alloy wire is composed of acopper alloy having a specific composition including Fe, P and Sn in aspecific range, and is further excellently conductive and excellent instrength, and in addition, also excellent in impact resistance, as hasbeen described above. Therefore, by using the above-described copperalloy wire as a conductor of an electrical wire, it is possible toconstruct an electrical wire excellently conductive and excellent instrength and in addition, also excellent in impact resistance, andfurthermore, an electrical wire also having excellent fatigueresistance, excellently fixing a terminal such as a crimp terminal, andhaving excellent impact resistance in a state with the terminal attachedthereto.

(11) A copper alloy stranded wire according to one aspect of the presentdisclosure is

-   -   formed of a plurality of copper alloy wires according to        item (10) stranded together.

The above copper alloy stranded wire substantially maintains thecomposition and characteristics of the copper alloy wire of the aboveitem (10), and is thus excellently conductive and excellent in strength,and in addition, also excellent in impact resistance. Therefore, byusing the above-described copper alloy stranded wire as a conductor ofan electrical wire, it is possible to construct an electrical wire whichis excellently conductive and excellent in strength and in addition,also excellent in impact resistance, and furthermore, an electrical wirealso having excellent fatigue resistance, excellently fixing a terminalsuch as a crimp terminal, and having excellent impact resistance in astate with the terminal attached thereto.

(12) An example of the above-described copper alloy stranded wireincludes

-   -   an embodiment in which an impact resistance energy in a state        with a terminal attached is 1.5 J/m or more.

In the above embodiment, an impact resistance energy in a state with aterminal attached is high. A covered electrical wire comprising a copperalloy stranded wire of the above embodiment as a conductor and aninsulating covering layer can construct a covered electrical wire havinga higher impact resistance energy in a state with a terminal attachedthereto, typically the covered electrical wire of the above item (6).Thus the above-described embodiment is excellently conductive andexcellent in strength, and excellent in impact resistance, and inaddition it can be suitably used for a conductor of a covered electricalwire which is further excellent in impact resistance in a state with aterminal attached thereto, a terminal-equipped electrical wire, and thelike.

(13) An example of the above-described copper alloy stranded wireincludes

-   -   an embodiment in which the copper alloy stranded wire alone has        an impact resistance energy of 4 J/m or more.

In the above embodiment, the copper alloy stranded wire per se has highimpact resistance energy. A covered electrical wire comprising a copperalloy stranded wire of the above embodiment as a conductor and aninsulating covering layer can construct a covered electrical wire havinghigher impact resistance energy, typically the covered electrical wireof the above item (7). Thus the above-described embodiment can besuitably applied to a conductor of a covered electrical wire, aterminal-equipped electrical wire, and the like which are excellentlyconductive and excellent in strength, and in addition, further excellentin impact resistance.

Details of Embodiments of the Present Invention

Hereinafter, the present invention will be described in embodiments indetail with reference to the drawings, as appropriate. In the figures,identical reference characters denote identically named components. Acontent of an element shall be a proportion by mass (% by mass or ppm bymass) unless otherwise specified.

[Copper Alloy Wire]

A copper alloy wire 1 of an embodiment is used as a conductor of anelectrical wire such as a covered electrical wire 3 (see FIG. 1), and iscomposed of a copper alloy containing specific additive elements in aspecific range. The copper alloy is a Fe—P—Sn—Cu alloy which contains Feat 0.1% or more and 1.6% or less, P at 0.05% or more and 0.7% or less,Sn at 0.05% or more and 0.7% or less, with the balance being Cu andimpurities. The impurities are mainly inevitable impurities. Inaddition, copper alloy wire 1 of an embodiment has a tensile strength of385 MPa or more and a work-hardening exponent of 0.1 or more.

Initially, a composition of the copper alloy will be described in detailfor each element.

(Composition)

⋅Fe

Fe is present mainly such that it precipitates at a matrix phase, or Cu,and contributes to enhancing strength such as tensile strength.

When Fe is contained in an amount of 0.1% or more, a precipitateincluding Fe and P can be produced satisfactorily, and by enhancedprecipitation, copper alloy wire 1 can be excellent in strength.Further, the precipitation can suppress solid solution of P in thematrix phase to provide copper alloy wire 1 with high conductivity.Although depending on the amount of P and the manufacturing conditions,the strength of copper alloy wire 1 tends to increase as the Fe contentincreases. If high strength or the like is desired, the Fe content canbe 0.2% or more, even more than 0.35%, 0.4% or more, 0.45% or more.

Fe contained in a range of 1.6% or less helps to suppress coarsening ofFe-containing precipitates and the like. This provides a wire which canreduce breakage starting from coarse precipitates and thus be excellentin strength, and in addition, is hard to break in its production processwhen undergoing wire-drawing or the like, and is thus also excellent inmanufacturability. Although depending on the amount of P and themanufacturing conditions, the smaller the Fe content is, the easier itis to suppress coarsening of precipitates described above and the like.When it is desired to suppress coarsening of precipitates (and hencereduce breakage and a break in the wire), and the like, the Fe contentcan be 1.5% or less, and even 1.2% or less, 1.0% or less, less than0.9%.

⋅P

In copper alloy wire 1, P mainly exists as a precipitate together withFe and contributes to improvement in strength such as tensile strength,that is, mainly functions as a precipitation enhancing element.

When P is contained in an amount of 0.05% or more, a precipitateincluding Fe and P can be produced satisfactorily, and by enhancedprecipitation, copper alloy wire 1 can be excellent in strength.Although depending on the amount of Fe and the manufacturing conditions,the strength of copper alloy wire 1 tends to increase as the P contentincreases. If high strength or the like is desired, the P content can bemore than 0.1%, and even 0.11% or more, 0.12% or more. It is to be notedthat it is permitted that a portion of the P contained functions as adeoxidizing agent and as a result is present as an oxide in the matrixphase.

P contained in a range of 0.7% or less helps to suppress coarsening ofFe and P-containing precipitates and the like and can reduce breakage, abreak in the wire, and the like. Although depending on the amount of Feand the manufacturing conditions, the smaller the P content is, theeasier it is to suppress the coarsening described above. When it isdesired to suppress coarsening of precipitates (and hence reducebreakage and a break in the wire), and the like, the P content can be0.6% or less, even 0.5 or less, 0.35% or less, 0.3% or less, 0.25% orless.

⋅Fe/P

In addition to containing Fe and P in the above specified ranges, whenFe is appropriately included relative to P, especially when Fe iscontained in an amount equal to or greater than P, it is easy to causeFe and P to be present as a compound. As a result, enhancedprecipitation can effectively enhance strength, as appropriate, andexcessive solid solution of P can be reduced to effectively maintain thematrix phase's high conductivity, as appropriate, and copper alloy wire1 can be excellently conductive and in addition, have high strength.

Quantitatively, the above copper alloy has a ratio of an Fe contentrelative to a P content, i.e., Fe/P, of 1.0 or more by mass. Fe/P of 1.0or more allows enhanced precipitation and thereby a satisfactorystrength enhancement effect, as described above, and hence excellentstrength. If further high strength or the like is desired, Fe/P can be1.5 or more, even 2.0 or more, 2.2 or more. Fe/P of 2.0 or more tends toallow the copper alloy to be more excellently conductive. Fe/P of 4.0 ormore allows the copper alloy to be excellently conductive and inaddition, excellent in strength. Larger Fe/P tends to allow the copperalloy to be further excellently conductive, and can be greater than 4.0,and even 4.1 or more. While Fe/P can be selected within a range forexample of 30 or less, Fe/P of 20 or less, even 15 or less, 10 or lesshelp to suppress coarsening of precipitates caused by excessive Fe.

⋅Sn

Sn is present mainly in the form of a solid solution in the matrixphase, or Cu, and contributes to improvement in strength such as tensilestrength, i.e., mainly functions as a solid solution enhancing element.

When Sn is contained in an amount of 0.05% or more, copper alloy wire 1can be further excellent in strength. The larger the Sn content is, theeasier it is to have higher strength. When high strength is desired, theSn content can be set to 0.08% or more, even 0.1% or more, 0.12% ormore.

When Sn is contained in a range of 0.7% or less, reduction inconductivity attributed to excessive solid solution of Sn in Cu can besuppressed and copper alloy wire 1 can have high conductivity. Inaddition, reduction in workability caused by excessive solid solution ofSn can be suppressed, so that wire-drawing or similar plastic workingcan be easily done and excellent manufacturability can also be obtained.When high conductivity and satisfactory workability are desired, the Sncontent can be 0.6% or less, even 0.55% or less, 0.5% or less.

Copper alloy wire 1 of an embodiment has high strength by enhancedprecipitation of Fe and P and enhanced solid solution of Sn as describedabove. Therefore, even when artificial aging and softening are performedin the manufacturing process, significantly strong and tough copperalloy wire 1 can be obtained having high strength while also havinglarge elongation or the like.

⋅C, Si, Mn

A copper alloy constituting copper alloy wire 1 of an embodiment caninclude an element having a deoxidizing effect for Fe, P, Sn and thelike. Specifically, the copper alloy may contain one or more elementsselected from C, Si and Mn in an amount of 10 ppm or more and 500 ppm orless in total as a proportion by mass.

If the manufacturing process is done in an oxygen-containing atmospheresuch as the air, elements such as Fe, P, Sn and the like may beoxidized. If these elements become oxides, the above-describedprecipitates and the like cannot be appropriately formed and/or solidsolution cannot be provided in the matrix phase, and accordingly, highconductivity and high strength by containing Fe and P and enhanced solidsolution by containing Sn may not be effectively obtained asappropriate. These oxides serve as points allowing breakage to start inwire-drawing or the like, and may invite reduction in productivity.Including at least one element, preferably two elements, of C, Mn andSi, (in the latter case, C and Mn or C and Si are preferable), morepreferably, all of the three elements in a specific range more reliablyensures that Fe and P are precipitated to provide enhanced precipitationand high conductivity and ensures enhanced solid solution of Sn toprovide copper alloy wire 1 which is excellently conductive and has highstrength.

When the above total content is 10 ppm or more, oxidation of elementssuch as Fe, as described above, can be prevented. The higher the abovetotal content is, the easier it is to obtain an antioxidation effect,and the above total content can be 20 ppm or more, even 30 ppm or more.

If the above total content is 500 ppm or less, it is difficult to invitereduction in conductivity attributed to excessively containing thesedeoxidizer elements, and excellent conductivity can be provided. Thesmaller the above total content is, the easier it is to suppressreduction in conductivity, and accordingly, the above total content canbe 300 ppm or less, even 200 ppm or less, 150 ppm or less.

The content of C alone is preferably 10 ppm or more and 300 ppm or less,more preferably 10 ppm or more and 200 ppm or less, particularlypreferably 30 ppm or more and 150 ppm or less.

The content of Mn alone or the content of Si alone is preferably 5 ppmor more and 100 ppm or less, more preferably more than 5 ppm and 50 ppmor less. The total content of Mn and Si is preferably 10 ppm or more and200 ppm or less, more preferably more than 10 ppm and 100 ppm or less.

When C, Mn and Si are contained in the above described ranges,respectively, it is easy to satisfactorily obtain the above-describedantioxidation effect for elements such as Fe. For example, the contentof oxygen in the copper alloy can be 20 ppm or less, 15 ppm or less,even 10 ppm or less.

(Structure)

A copper alloy constituting copper alloy wire 1 of an embodiment mayhave a structure in which precipitates and/or crystallites including Feand P are dispersed. By having a structure in which precipitates or thelike are dispersed, preferably a structure in which fine precipitates orthe like are uniformly dispersed, it is expected to ensure high strengthby enhanced precipitation, and high conductivity by reduction of solidsolution of P or the like in Cu.

Further, the copper alloy may have a fine crystal structure. This helpsthe above-described precipitates or the like to be present such thatthey are uniformly dispersed, and further higher strength can beexpected. In addition, there are few coarse crystal grains that canserve as breakage starting points, which also helps to increasetoughness such as elongation and it is expected that further excellentimpact resistance is provided. Further, in that case, when copper alloywire 1 of the embodiment is used as a conductor of an electrical wiresuch as covered electrical wire 3 and a terminal such as a crimpterminal is attached to the conductor, the terminal can be firmly fixedand a force to fix the terminal can thus be easily increased.

Quantitatively, an average crystal grain size of 10 μm or less helps toobtain the effect described above, and it can be 7 μm or less, even 5 μmor less. The crystal grain size can be adjusted to have a predeterminedsize for example by adjusting manufacturing conditions (such as a degreeof working and a heat treatment temperature, etc., which are alsoapplied hereinafter) depending on the composition (Fe, P, Sn contents,the value of Fe/P etc., which are also applied hereinafter).

The average crystal grain size is measured as follows: A transversecross section polished with a cross section polisher (CP) is taken andobserved with a scanning electron microscope. From the observed image,an observation range of a predetermined area S₀ is taken and the numberN of all crystals present in the observation range is counted. Area S₀divided by the number N of crystals, i.e., S₀/N, is defined as an areaSg of each crystal grain, and the diameter of a circle having an areaequivalent to area Sg of the crystal grain is defined as a diameter R ofthe crystal grain. An average of diameters R of crystal grains isdefined as the average crystal grain size. The observation range can bea range in which the number N of crystals is 50 or more, or the entiretyof the transverse cross section. By making the observation rangesufficiently large as described above, it is possible to sufficientlyreduce an error caused by what is other than crystals that can bepresent in area S₀ (such as precipitates).

(Wire Diameter)

When copper alloy wire 1 of the embodiment is manufactured through aprocess, it can undergo wire-drawing with an adjusted working ratio (orcross section reduction ratio) or the like to have a wire diameter of apredetermined size. In particular, when copper alloy wire 1 is a thinwire having a wire diameter of 0.5 mm or less, it can be suitably usedfor a conductor of an electrical wire for which reduction in weight isdesired, e.g., a conductor for an electrical wire to be wired in anautomobile. The wire diameter can be 0.35 mm or less, even 0.25 mm orless.

(Cross Sectional Shape)

Copper alloy wire 1 of an embodiment has a transverse cross sectionalshape selected as appropriate. A representative example of copper alloywire 1 is a round wire having a circular transverse cross sectionalshape. The transverse cross sectional shape varies depending on theshape of a die used for wire-drawing, and the shape of a die when copperalloy wire 1 is a compressed stranded wire, etc. Copper alloy wire 1 canbe, for example, a quadrangular wire having a rectangular or similartransverse cross-sectional shape, a shaped wire having a hexagonal orother polygonal shape, an elliptical shape or the like. Copper alloywire 1 constituting the compressed stranded wire is typically a shapedwire having an indefinite transverse cross sectional shape.

(Characteristics)

According to an embodiment, copper alloy wire 1 is composed of a copperalloy having the above described specific composition, and is thusexcellently conductive and in addition, has high strength. It ismanufactured through an appropriate heat treatment to have highstrength, high toughness and high conductivity in a good balance. Copperalloy wire 1 of such an embodiment can be suitably used as a conductorfor covered electrical wire 3 or the like. In particular, copper alloywire 1 of an embodiment has a tensile strength as high as 385 MPa ormore and in addition, a work-hardening exponent of 0.1 or more, and isthus a wire member significantly effectively enhanced in strengththrough work hardening. For example, when copper alloy wire 1 is used asa conductor of an electrical wire such as covered electrical wire 3, anda terminal such as a crimp terminal is attached to the conductor bycrimping or the like, the conductor has a terminal attachment portion,which is a worked portion having undergone plastic working such ascompression-working. Although this worked portion has undergone plasticworking, such as compression-working, accompanied by a reduction incross section, it is harder than before plastic working and is enhancedin strength. Thus, the worked portion, that is, the terminal attachmentportion of the conductor and a vicinity thereof can be a less weak pointin strength. The portion of the conductor other than the terminalattachment portion has high strength, as has been described above, andaccordingly, the terminal-equipped electrical wire can as a whole havehigh strength. Furthermore, copper alloy wire 1 having high toughness asdescribed above also has excellent impact resistance in a state with aterminal attached. When copper alloy wire 1 has tensile strength of 390MPa or more, even 395 MPa or more, 400 MPa or more, in particular,higher strength is provided.

—Tensile Strength, Elongation at Break, and Conductivity

Copper alloy wire 1 of an embodiment satisfies at least one of: atensile strength of 400 MPa or more, an elongation at break of 5% ormore, and a conductivity of 60% IACS or more, preferably two thereof,more preferably all of the three. An example of copper alloy wire 1 hasa conductivity of 60% IACS or more and a tensile strength of 400 MPa ormore. Alternatively, an example of copper alloy wire 1 has an elongationat break of 5% or more.

When higher strength is desired, the tensile strength can be set to 405MPa or more, 410 MPa or more, even 415 MPa or more.

When higher toughness is desired, the elongation at break can be 6% ormore, 7% or more, 8% or more, 9.5% or more, even 10% or more.

When higher conductivity is desired, the conductivity can be set to 62%IACS or more, 63% IACS or more, even 65% IACS or more.

—Work Hardening Exponent

A work hardening exponent is defined as an exponent n of a true strain εin an equation of σ=C×ε^(n) where σ and ε represent true stress and truestrain, respectively, in a plastic strain region in a tensile test whena test force is applied in a uniaxial direction. In the above equation,C represents a strength parameter.

The above exponent n can be obtained by performing a tensile test usinga commercially available tensile tester, and preparing an S-S curve (seealso JIS G 2253 (2011)).

Larger work hardening exponents facilitate work hardening, and a thusworked portion can be effectively increased in strength through workhardening. A work hardening exponent of 0.11 or more, furthermore, 0.12or more, 0.13 or more, helps work hardening to effectively enhancestrength. Depending on the composition, the manufacturing conditions andthe like, it can be expected that the conductor comprising copper alloywire 1 has a terminal attachment portion which maintains a level ofstrength equivalent to that of the main wire portion of the conductor.The work hardening exponent varies depending on the composition, themanufacturing conditions and the like, and accordingly, its upper limitis not particularly specified.

The tensile strength, the elongation at break, the conductivity, and thework hardening exponent can be set as prescribed in magnitude byadjusting the composition, the manufacturing conditions and the like.For example, larger amounts of Fe, P, Sn and higher degrees ofwire-drawing (or thinning the wire) tend to increase tensile strength.For example, when wire-drawing is followed by a heat treatment performedat high temperature, elongation at break and conductivity tend to behigh and tensile strength tends to be low.

—Weldability

Copper alloy wire 1 of an embodiment also has excellent weldability asan effect. For example, when copper alloy wire 1 or a copper alloystranded wire 10 described later is used as a conductor of an electriccable and another conductor wire or the like is welded thereto at aportion for branching from the conductor, the welded portion is hard tobreak, and is thus strongly welded.

[Copper Alloy Stranded Wire]

Copper alloy stranded wire 10 of an embodiment uses copper alloy wire 1of an embodiment as an elemental wire, and is formed of a plurality ofcopper alloy wires 1 stranded together. Copper alloy stranded wire 10substantially maintains the composition, structure and characteristicsof copper alloy wire 1 serving as an elemental wire, and in addition,easily has a cross sectional area larger than in a case with a crosssectional area of a single elemental wire, and accordingly, can have anincreased force to receive impact and is thus further excellent inimpact resistance. In addition, when copper alloy stranded wire 10 iscompared with a solid wire having the same cross-sectional area, theformer is more easily bent and twisted and thus also excellent inbendability and twistability, and when it is used as a conductor of anelectrical wire, it is hard to break even when routed or repeatedlybent. Furthermore, copper alloy stranded wire 10 has a plurality ofcopper alloy wires 1 that are easily work-hardened, as described above,and when it is used as a conductor of an electrical wire such as coveredelectrical wire 3 and a terminal such as a crimp terminal is attachedthereto, the terminal can be further firmly fixed thereto. While FIG. 1shows copper alloy strand wire 10 composed of seven wires concentricallystranded together as an example, how many wires are stranded togetherand how can be changed as appropriate.

After being stranded together, copper alloy stranded wire 10 can becompressed and thus formed to be a compressed stranded wire (not shown).A compressed stranded wire is excellent in stability in a strandedstate, and when the compressed stranded wire is used as a conductor ofan electrical wire such as covered electrical wire 3, insulatingcovering layer 2 or the like is easily formed on the outer circumferenceof the conductor. In addition, when the compressed stranded wire iscompared with a simple strand, the former tends to have bettermechanical properties and in addition, can be smaller in diameter thanthe latter.

Copper alloy stranded wire 10 can have a wire diameter, across-sectional area, a stranding pitch, and the like appropriatelyselected depending on the wire diameter of copper alloy wire 1, thecross-sectional area of copper alloy wire 1, the number of copper alloywires is stranded together, and the like.

When copper alloy stranded wire 10 has a cross-sectional area forexample of 0.03 mm² or more, the conductor will have a largecross-sectional area, and hence be small in electric resistance andexcellently conductive. Further, when copper alloy stranded wire 10 isused as a conductor of an electrical wire such as covered electricalwire 3 and a terminal such as a crimp terminal is attached to theconductor, the conductor having a somewhat large cross sectional areafacilitates attaching the terminal thereto. Furthermore, as has beendescribed above, the terminal can be firmly fixed to copper alloystranded wire 10, and excellent impact resistance in a state with theterminal attached is also provided. The cross-sectional area can be 0.1mm² or more. When the cross-sectional area is, for example, 0.5 mm² orless, copper alloy stranded wire 10 can be lightweight.

When copper alloy stranded wire 10 has a stranding pitch for example of10 mm or more, even elemental wires (or copper alloy wires 1) which arethin wires having a wire diameter of 0.5 mm or less can be easilystranded together, and copper alloy stranded wire 10 is thus excellentin manufacturability. A stranding pitch for example of 20 mm or lessprevents the strand from being loosened when bent, and excellentbendability is thus provided.

—Impact Resistance Energy in State with Terminal Attached

Copper alloy stranded wire 10 of an embodiment is composed of elementalwire that is copper alloy wire 1 composed of a specific copper alloy asdescribed above, and when stranded wire 10 is used for a conductor of acovered electrical wire or the like and a terminal such as crimpterminal is attached to an end of the conductor, and in that conditionstranded wire 10 receives an impact, the terminal attachment portion anda vicinity thereof is hard to break. Quantitatively, copper alloystranded wire 10 with the terminal attached thereto as described abovehas impact resistance energy of 1.5 J/m or more as an example. Thegreater the impact resistance energy in the state with the terminalattached is, the harder the terminal attachment portion and a vicinitythereof are to break when they receive an impact. When such a copperalloy stranded wire 10 is used as a conductor, a covered electrical wireor the like which is excellent in impact resistance in a state with aterminal attached thereto can be constructed. Copper alloy stranded wire10 in the state with the terminal attached thereto preferably has animpact resistance energy of 1.6 J/m or more, more preferably 1.7 J/m ormore, and no upper limit therefor is particularly specified.

—Impact Resistance Energy

Copper alloy stranded wire 10 of an embodiment is composed of elementalwire that is copper alloy wire 1 composed of a specific copper alloy asdescribed above, and when stranded wire 10 receives an impact, it ishard to break. Quantitatively, copper alloy stranded wire 10 alone hasan impact resistance energy of 4 J/m. The larger the impact resistanceenergy is, the harder copper alloy stranded wire 10 per se is to breakwhen it receives an impact. When such a copper alloy stranded wire 10 isused as a conductor, a covered electrical wire or the like excellent inimpact resistance can be constructed. Copper alloy stranded wire 10preferably has an impact resistance energy of 4.2 J/m or more, morepreferably 4.5 J/m or more, and no upper limit therefor is particularlyspecified.

Note that it is preferable that copper alloy wire 1 in the form of asolid wire also have an impact resistance energy satisfying the aboverange in a state with a terminal attached thereto and a state in whichthe wire is alone without any terminal attached thereto. When copperalloy stranded wire 10 of an embodiment in a state with a terminalattached thereto and a state in which the wire is alone without anyterminal attached thereto is compared with copper alloy wire 1 in theform of a solid wire in the same states, the former tends to have higherimpact resistance energy than the latter.

[Covered Electrical Wire]

While copper alloy wire 1 and copper alloy stranded wire 10 of anembodiment can be used as a conductor as they are, copper alloy wire 1and copper alloy stranded wire 10 surrounded by an insulating coveringlayer are excellently insulative. Covered electrical wire 3 of anembodiment includes a conductor and insulating covering layer 2surrounding the conductor, and the conductor is copper alloy strandedwire 10 of an embodiment. Another embodiment of the covered electricalwire is a covered electrical wire including a conductor implemented bycopper alloy wire 1 (in the form of a solid wire). FIG. 1 shows anexample with a conductor including copper alloy stranded wire 10.

Insulating covering layer 2 is composed of an insulating material forexample including polyvinyl chloride (PVC), a non-halogen resin (forexample, polypropylene (PP)), an excellently flame retardant material,and the like. Known insulating materials can be used.

Insulating covering layer 2 can be selected in thickness as appropriatedepending on insulating strength as prescribed, and is thus notparticularly limited in thickness.

—Terminal Fixing Force

As has been described above, covered electrical wire 3 of an embodimentcomprises a conductor comprising copper alloy stranded wire 10 composedof an elemental wire that is copper alloy wire 1 composed of a specificcopper alloy, and in a state with a terminal such as a crimp terminalattached thereto by crimping or the like, covered electrical wire 3allows the terminal to be firmly fixed thereto. Quantitatively, coveredelectrical wire 3 has a terminal fixing force of 45 N or more. Largerterminal fixing force is preferable as it can firmly fix the terminaland easily maintains covered electrical wire 3 (the conductor) and theterminal in a connected state. The terminal fixing force is preferably50 N or more, more than 55 N, further preferably 58 N or more, and noupper limit therefor is particularly specified.

—Impact Resistance Energy

When covered electrical wire 3 of an embodiment in a state with aterminal attached thereto and a state in which the wire is alone withoutany terminal attached thereto is compared with a bare conductor withoutinsulating covering layer 2, that is, copper alloy stranded wire 10 ofan embodiment, the former tends to have higher impact resistance energythan the latter. Depending on insulating covering layer 2's constituentmaterials, thickness or the like, covered electrical wire 3 in the statewith the terminal attached thereto and covered electrical wire 3 alonemay have impact resistance energy further increased as compared with thebare conductor. Quantitatively, covered electrical wire 3 in the statewith the terminal attached thereto has an impact resistance energy of 3J/m or more. When covered electrical wire 3 in the state with theterminal attached thereto has larger impact resistance energy, theterminal attachment portion is harder to break when it receives animpact, and the impact resistance energy is preferably 3.2 J/m or more,more preferably 3.5 J/m or more, and no upper limit therefor isparticularly specified.

Furthermore, quantitatively, covered electrical wire 3 alone has animpact resistance energy (hereinafter also referred to as the mainwire's impact resistance energy) of 6 J/m or more. The larger the mainwire's impact resistance energy is, the harder the wire is to break whenit receives an impact, and it is preferably 6.5 J/m or more, morepreferably 7 J/m or more, and 8 J/m or more, and no upper limit thereforis particularly specified.

When covered electrical wire 3 has insulating covering layer 2 removedtherefrom to be a conductor alone, that is, copper alloy stranded wire10 alone, and this conductor has measured its impact resistance energyin a state with a terminal attached thereto and its impact resistanceenergy in a state in which the conductor is alone without any terminalattached thereto, the conductor assumes substantially the same value ascopper alloy stranded wire 10 as described above. Specifically, theconductor comprised by covered electrical wire 3 in the state with theterminal attached to the conductor has an impact resistance energy of1.5 J/m or more, and the conductor comprised by covered electrical wire3 has an impact resistance energy of 4 J/m or more.

Note that it is preferable that a covered electrical wire comprisingcopper alloy wire 1 which is a solid wire as a conductor also have atleast one of the terminal fixing force, the impact resistance energy inthe state with the terminal attached, and the main wire's impactresistance energy satisfying the above-described range. When coveredelectrical wire 3 of an embodiment with a conductor comprising copperalloy stranded wire 10 is compared with a covered electrical wire usingcopper alloy wire 1 which is a solid wire as a conductor, the formertends to have a larger terminal fixing force, a larger impact resistanceenergy in the state with the terminal attached, and a larger impactresistance energy of the main wire than the latter.

Covered electrical wire 3 or the like of an embodiment can have theterminal fixing force, the impact resistance energy in the state withthe terminal attached, and the main wire's impact resistance energy tobe of a magnitude as prescribed by adjusting the composition,manufacturing conditions and the like of copper alloy wire 1, theconstituent materials, thickness and the like of the insulating coveringlayer 2, and the like. For example, copper alloy wire 1 has itscomposition, manufacturing conditions and the like adjusted so thatcharacteristic parameters such as the aforementioned tensile strength,elongation at break, conductivity, work hardening exponent and the likesatisfy the above specified ranges.

[Terminal Equipped Electrical Wire]

As shown in FIG. 2, a terminal-equipped electrical wire 4 of anembodiment includes covered electrical wire 3 of an embodiment and aterminal 5 attached to an end of covered electrical wire 3. Herein,terminal 5 is a crimp terminal including at one end a female or malefitting portion 52 and at the other end an insulation barrel portion 54for gripping insulating covering layer 2, and at an intermediate portiona wire barrel portion 50 for gripping the conductor (in FIG. 2, copperalloy stranded wire 10) by way of example. The crimp terminal is crimpedto an end of the conductor that is exposed by removing insulatingcovering layer 2 at an end of covered electrical wire 3, and the crimpterminal is electrically and mechanically connected to the conductor.Other than a crimping type such as a crimp terminal, terminal 5 is of aweld type to which a molten conductor is connected as one example. Aterminal-equipped electrical wire according to another embodimentcomprises a covered electrical wire using copper alloy wire 1 (a solidwire) as a conductor.

Terminal-equipped electrical wire 4 may include an embodiment in whichone terminal 5 is attached to each covered electrical wire 3, as shownin FIG. 2, and an embodiment in which one terminal 5 is provided for aplurality of covered electrical wires 3. That is, terminal-equippedelectrical wire 4 includes an embodiment including one coveredelectrical wire 3 and one terminal 5, an embodiment including aplurality of covered electrical wires 3 and one terminal 5, and anembodiment including a plurality of covered electrical wires 3 and aplurality of terminals 5. When a plurality of electrical wires areprovided, using a binder to bind the plurality of electrical wirestogether helps to easily handle terminal-equipped electrical wire 4.

[Characteristics of Copper Alloy Wire, Copper Alloy Stranded Wire,Covered Electrical Wire, Terminal-Equipped Electrical Wire]

According to an embodiment, each elemental wire of copper alloy strandedwire 10, each elemental wire constituting the conductor of coveredelectrical wire 3, and each elemental wire constituting the conductor ofterminal-equipped electrical wire 4 all maintain copper alloy wire 1'scomposition, structure and characteristics or have characteristicsequivalent thereto. Specifically, each of the above elemental wires hasa tensile strength of 385 MPa or more and a work-hardening exponent of0.1 or more. An example of each of the above elemental wires satisfiesat least one of a tensile strength of 400 MPa or more, an elongation atbreak of 5% or more, and a conductivity of 60% IACS or more.

Terminal 5 such as a crimp terminal which terminal-equipped electricalwire 4 is per se equipped with can be used as a terminal used formeasuring terminal-equipped electrical wire 4's terminal fixing forceand impact resistance energy in the state with the terminal attached.

[Application of Copper Alloy Wire, Copper Alloy Stranded Wire, CoveredElectrical Wire, and Terminal-Equipped Electrical Wire]

Covered electrical wire 3 of an embodiment can be used for wiringportions of various electric devices and the like. In particular,covered electrical wire 3 according to an embodiment is suitably used inapplications with terminal 5 attached to an end of covered electricalwire 3, e.g., transporting vehicles such as automobiles and airplanes,controllers for industrial robots, and the like. Terminal-equippedelectrical wire 4 of an embodiment can be used for wiring of variouselectric devices such as the above-described transporting vehicles andcontrollers. Covered electrical wire 3 and terminal-equipped electricalwire 4 of such an embodiment can be suitably used as constituentelements of various wire harnesses such as automobile wire harnesses.The wire harness including covered electrical wire 3 andterminal-equipped electrical wire 4 according to an embodiment easilymaintains connection with terminal 5 and can thus enhance reliability.Copper alloy wire 1 of an embodiment and copper alloy stranded wire 10of an embodiment can be used as a conductor of an electrical wire suchas covered electrical wire 3 and terminal-equipped electrical wire 4.

[Effect]

Copper alloy wire 1 of an embodiment is composed of a specific copperalloy containing Fe, P and Sn in a specific range, and is thusexcellently conductive and excellent in strength, and in addition, alsoexcellent in impact resistance. In particular, copper alloy wire 1 of anembodiment has high strength as high as 385 MPa or more and in addition,a work-hardening exponent as large as 0.1 or more, and when copper alloywire 1 has terminal 5 such as a crimp terminal crimped thereto, copperalloy wire 1 can firmly fix terminal 5, and in addition, it is alsoexcellent in impact resistance in a state with terminal 5 attached.Copper alloy stranded wire 10 of an embodiment having copper alloy wire1 of an embodiment as an elemental wire is similarly excellentlyconductive and excellent in strength, and in addition, also excellent inimpact resistance. Furthermore, when copper alloy stranded wire 10 of anembodiment is used for a conductor for covered electrical wire 3 or thelike and has terminal 5 attached thereto, copper alloy stranded wire 10can firmly fix terminal 5, and in addition, it is also excellent inimpact resistance in a state with terminal 5 attached.

Covered electrical wire 3 of an embodiment comprises a conductorcomprising copper alloy stranded wire 10 of an embodiment comprisingcopper alloy wire 1 of an embodiment as an elemental wire, and coveredelectrical wire 3 is thus excellently conductive and excellent instrength, and in addition, also excellent in impact resistance.Furthermore, when covered electrical wire 3 has terminal 5 such as acrimp terminal crimped thereto, covered electrical wire 3 can firmly fixterminal 5, and in addition, it is also excellent in impact resistancein a state with the terminal attached.

Terminal-equipped electrical wire 4 of an embodiment that comprisescovered electrical wire 3 of an embodiment is excellently conductive andexcellent in strength, and in addition, also excellent in impactresistance. Furthermore, terminal-equipped electrical wire 4 can firmlyfix terminal 5, and in addition, it is also excellent in impactresistance in a state with the terminal attached.

These effects will specifically be described in Test Examples 1 and 2.

[Manufacturing Method]

Copper alloy wire 1, copper alloy stranded wire 10, covered electricalwire 3, and terminal-equipped electrical wire 4 according to anembodiment can be manufactured by a manufacturing method including, forexample, the following steps. Hereinafter, each step will be outlined.

(Copper Alloy Wire)

<Continuous Casting Step> A copper alloy having a specific compositionincluding Fe, P and Sn in a specified range as described above is moltenand continuously cast to prepare a cast material.

<Wire-Drawing Step> The cast material or a worked material obtained byworking the cast material is subjected to wire-drawing to produce awire-drawn member.

<Heat Treatment Step> The wire-drawn member is subjected to a heattreatment to produce a heat-treated member.

Typically, this heat treatment is assumed to include artificial aging toprovide precipitates containing Fe and P from a copper alloy includingFe and P in a state of solid solution, and softening to improveelongation of a wire-drawn member work-hardened by wire-drawing done toattain a final wire diameter. Hereinafter, this heat treatment will bereferred to as an aging/softening treatment.

A heat treatment other than the aging/softening treatment can includethe following solution treatment.

The solution treatment is a heat treatment one purpose of which is toprovide a supersaturated solid solution, and the treatment can beapplied at any time after the continuous casting step before theaging/softening treatment.

(Copper Alloy Stranded Wire)

Manufacturing copper alloy stranded wire 10 comprises theabove-described <continuous casting step>, <wire drawing step> and <heattreatment step> and in addition thereto, the following wire strandingstep. When forming a compressed stranded wire, the following compressionstep is further comprised.

<Wire stranding step> A plurality of wire-drawn members each asdescribed above are twisted together to manufacture a stranded wire.Alternatively, a plurality of heat-treated members each as describedabove are twisted together to manufacture a stranded wire.

<Compression Step> The stranded wire is compression-molded into apredetermined shape to produce a compressed stranded wire.

When the <wire stranding step> and the <compression step> are comprised,the <heat treatment step> is performed to apply the aging/softening heattreatment to the stranded wire or the compressed stranded wire. Whenproducing a stranded wire or compressed stranded wire of the above heattreated material, a second heat treatment step of further subjecting thestranded wire or the compressed stranded wire to an aging/softening heattreatment may be comprised or dispensed with. When the aging/softeningheat treatment is performed a plurality of times, a heat treatmentcondition can be adjusted so that the above-described characteristicparameter satisfies a specific range. By adjusting the heat treatmentcondition, for example it is easy to suppress growth of crystal grainsto form a fine crystal structure, and it is easy to have high strengthand high elongation.

(Covered Electrical Wire)

Manufacturing covered electrical wire 3 comprising copper alloy strandedwire 10, a covered electrical wire comprising copper alloy wire 1 in theform of a solid wire, and the like comprises a covering step to form aninsulating covering layer to surround a copper alloy wire (copper alloywire 1 of an embodiment) manufactured in the above-described copperalloy wire manufacturing method or a copper alloy stranded wire (copperalloy stranded wire 10 of an embodiment) manufactured in theabove-described copper alloy stranded wire manufacturing method. Theinsulating covering layer can be formed in known methods such asextrusion-coating and powder-coating.

(Terminal-Equipped Electrical Wire)

Manufacturing terminal-equipped electrical wire 4 comprises a crimpingstep in which the insulating covering layer is removed at an end of acovered electrical wire that is manufactured by the above-describedmethod of manufacturing a covered electrical wire (e.g., coveredelectrical wire 3 or the like of an embodiment) to expose a conductorand a terminal is attached to the exposed conductor.

Hereinafter, the continuous casting step, the wire drawing step, and theheat treatment step will be described in detail.

<Continuous Casting Step>

In this step, a copper alloy having a specific composition including Fe,P and Sn in a specified range as described above is molten andcontinuously cast to prepare a cast material. Melting the copper alloyin a vacuum atmosphere can prevent oxidation of elements such as Fe, P,Sn. In contrast, doing so in an atmosphere of the air eliminates thenecessity of controlling the atmosphere and can thus contribute toincreased productivity. In that case, to prevent the above elements fromoxidation due to oxygen in the atmosphere, it is preferable to use theabove-described C, Mn, Si (or deoxidizer elements).

C (carbon) is added for example by covering the surface of the melt withcharcoal chips, charcoal powder or the like. In that case, C can besupplied into the melt from charcoal chips, charcoal powder or the likein a vicinity of the surface of the melt.

Mn and Si may be added by preparing a source material containing theelements, and mixing the source material with the melt. In that case,even if a portion exposed in the surface of the melt through gaps formedby the charcoal chips or charcoal powder comes into contact with oxygenin the atmosphere, the portion can be prevented from oxidation in thevicinity of the surface of the melt. Examples of the source materialinclude Mn and Si as simple substances, Mn or Si and Fe alloyedtogether, and the like.

In addition to adding the above deoxidizer element, it is preferable touse a crucible, a mold or the like of a high-purity carbon materialhaving few impurities as doing so makes it difficult to introduceimpurities into the melt.

Note that copper alloy wire 1 of an embodiment typically causes Fe and Pto be present as precipitates and Sn to be present as a solid solution.Therefore, it is preferable that copper alloy wire 1 is manufacturedthrough a process comprising a process for forming a supersaturatedsolid solution. For example, a solution treatment step for performing asolution treatment can be separately provided. In that case, thesupersaturated solid solution can be formed at any time. When continuouscasting is performed with an increased cooling rate to prepare a castmaterial of a supersaturated solid solution, it is not necessary toseparately provide a solution treatment step, and copper alloy wire 1can be manufactured which finally has excellent electrical andmechanical properties and is thus suitable for a conductor of coveredelectrical wire 3 or the like. Accordingly, as a method formanufacturing copper alloy wire 1, it is proposed to perform continuouscasting, and applying a fast cooling rate to a cooling process toprovide rapid cooling, in particular.

As a continuous casting method, various methods can be used such as abelt and wheel method, a twin belt method, an up-cast method and thelike. In particular, the up-cast method is preferred because it canreduce impurities such as oxygen and easily prevent oxidation of Cu, Fe,P, Sn and the like. The cooling rate in the cooling process ispreferably higher than 5° C./sec, more preferably higher than 10°C./sec, 15° C./sec or higher.

Various types of plastic working, cutting and other processing can beapplied to the cast material. Plastic working includes conformextrusion, rolling (hot, warm, cold), and the like. Cutting includesstripping and the like. These workings can reduce the cast material'ssurface defects, so that in wire drawing, a break of a wire can bereduced to contribute to increased productivity. In particular, whenthese workings are applied to an upcast material, the resultant wire ishard to break.

<Wire Drawing Step>

In this step, the cast material, the cast material having been worked,or the like undergoes at least one pass, typically a plurality ofpasses, of wire-drawing (cold) to prepare a wire-drawn member having afinal wire diameter. When a plurality of passes is applied, a degree ofworking for each pass may be appropriately adjusted depending on thecomposition, the final wire diameter, and the like. When wire drawing ispreceded by an intermediate heat treatment, a plurality of passes andthe like, the intermediate heat treatment can be performed betweenpasses to enhance workability. The intermediate heat treatment can bedone under a condition which is appropriately selected so as to obtaindesired workability.

<Heat Treatment Step>

In this step, an aging/softening treatment aimed at artificial aging andsoftening as described above is performed. This aging/softeningtreatment can enhance precipitation of precipitates or the like toprovide effectively increased strength and can reduce solid solution inCu to effectively maintain high conductivity, as described above,satisfactorily, and copper alloy wire 1, copper alloy stranded wire 10and the like which are excellently conductive and excellent in strengthcan thus be obtained. In addition, by the aging/softening treatment, itis possible to improve toughness such as elongation while maintaininghigh strength, and copper alloy wire 1 and copper alloy stranded wire 10also excellent in toughness can be obtained.

The aging/softening treatment, for a batch process, is performed under acondition indicated for example as follows:

(Heat treatment temperature) 350° C. or higher and 550° C. or lower,preferably 400° C. or higher and 500° C. or lower

(Holding time) more than 4 hours and 40 hours or less, preferably 5hours or more and 20 hours or less.

The holding time as referred to herein is a period of time for which theabove heat treatment temperature is held, and it excludes a period oftime for which temperature is raised and that for which temperature islowered.

The heat treatment temperature and the holding time may be selected fromthe above ranges depending on the composition, the working state, andthe like. In particular, when the heat treatment temperature is selectedfrom a range of 400° C. or higher and lower than 500° C. and the holdingtime is a relatively a long period of time of more than 4 hours, even 5hours or more, 6 hours or more, it is easy to obtain copper alloy wire 1having a high strength of 385 MPa or more and also having high toughnessand excellent impact resistance. For a more specific condition, see TestExamples 1 and 2 described later. Note that continuous processing suchas a furnace type or an energization type may be used.

For a given composition, a heat treatment performed at high temperaturewithin the above range tends to improve conductivity, elongation atbreak, impact resistance energy in a state with a terminal attached, andthe main wire's impact resistance energy. A heat treatment having a lowtemperature can suppress growth of crystal grains and also tends toimprove tensile strength. When the above precipitate is sufficientlyprecipitated, high strength is provided, and in addition, conductivitytends to be improved.

In addition, an aging treatment can mainly be performed duringwire-drawing, and a softening treatment can mainly be applied to a finalstranded fire. The aging treatment and the softening treatment may beperformed under conditions selected from the conditions of theaging/softening treatment described above.

Test Example 1

Copper alloy wires of various compositions and covered electrical wiresusing the obtained copper alloy wires as conductors were manufacturedunder various manufacturing conditions and had their characteristicsexamined.

Each copper alloy wire was manufactured in any one of manufacturingpatterns (A) to (C) shown in Table 1 (for final wire diameters, see wirediameters (mm) shown in table 3). Each covered electrical wire wasmanufactured in any one of manufacturing patterns (a) to (c) shown inTable 1.

TABLE 1 copper alloy wire manufacturing patterns covered electrical wiremanufacturing patterns (A) (B) (C) (a) (b) (c) continuous castingcontinuous casting continuous casting continuous casting continuouscasting continuous casting (wire diameter: (wire diameter: (wirediameter: (wire diameter: (wire diameter: (wire diameter: φ30 mm to φ30mm to φ9.5 mm) φ30 mm to φ30 mm to φ9.5 mm) 12.5 mm) 12.5 mm) 12.5 mm)12.5 mm) ↓ ↓ ↓ ↓ ↓ ↓ conform extrusion cold rolling wire drawing conformextrusion cold rolling wire drawing (wire diameter: (wire diameter:(wire diameter in (wire diameter: (wire diameter: (wire diameter: φ9.5mm) φ9.5 mm) table 3) φ9.5 mm) φ9.5 mm) φ0.16 mm) ↓ ↓ ↓ ↓ ↓ ↓ wiredrawing stripping heat treatment wire drawing stripping stranding 7wires together → (wire diameter: (wire diameter: (conditions in (wirediameter: (wire diameter: compressed stranded wire φ0.35 mm φ8 mm) table2) φ0.16 mm) φ8 mm) (cross section: 0.13 mm²) or φ0.16 mm) ↓ ↓ ↓ ↓ ↓heat treatment wire drawing stranding 7 wires wire drawing heattreatment (conditions in (wire diameter: together → (wire diameter:(conditions in table 2) table 2) φ0.35 mm compressed φ0.16 mm) or φ0.16mm) stranded wire (cross section: 0.13 mm²) ↓ ↓ ↓ ↓ heat treatment heattreatment stranding 7 wires together → extruding insulating material(conditions in (conditions in table 2) compressed stranded wire (PVC orPP, table 2) (cross section: 0.13 mm²) thickness: 0.1 mm to 0.3 mm) ↓ ↓extruding heat treatment insulating material (conditions in table 2)(PVC or PP, thickness: 0.1 mm to 0.3 mm) ↓ extruding insulating material(PVC or PP, thickness: 0.1 mm to 0.3 mm)

In any manufacturing pattern, the following cast material was prepared.

(Cast Material)

Electric copper (purity: 99.99% or higher) and a master alloy containingeach element shown in Table 2 or the element in the form of a simplesubstance were prepared as a raw material. The prepared raw material wasmolten in an atmosphere of the air in a crucible made of high puritycarbon (with impurity in an amount of 20 ppm by mass or less) to preparemolten copper alloy. The copper alloy has compositions (with the balancebeing Cu and impurities) shown in Table 2.

The molten copper alloy and a high purity carbon mold (with impurity inan amount of 20 ppm by mass or less) were used in an upcast method toprepare a continuous cast material (wire diameter: selected from a rangeof φ30 mm to φ12.5 mm, or φ9.5 mm) having a circular cross section. Thecooling rate exceeded 10° C./sec.

(Covered Electrical Wire)

In manufacturing patterns (a) to (c), as well as manufacturing patterns(A) to (C) for copper alloy wires, a wire-drawn member having a wirediameter of φ0.16 mm was prepared and 7 such wire-drawn members weretwisted together and subsequently compression-molded to prepare acompressed stranded wire having a transverse cross sectional area of0.13 mm² (0.13 sq) which was in turn subjected to a heat treatment (anaging/softening treatment) under the conditions shown in Table 2. Table2 indicates a heat treatment condition for time (h), which is a periodof time for which a temperature (° C.) indicated in table 2 is held, andit excludes a period of time for which temperature is raised and thatfor which temperature is lowered. The obtained heat-treated member wassurrounded by polyvinyl chloride (PVC) or polypropylene (PP) extruded tohave a predetermined thickness (selected from 0.1 mm to 0.3 mm) to thusform an insulating covering layer to thus manufacture a coveredelectrical wire with the above heat-treated member as a conductor.

TABLE 2 composition heat trace treatment mass components conditionssample (% by mass) ratio (ppm by mass) temperature time No. Cu Fe P SnFe/P C Mn Si (° C.) (h) 1-1 Bal. 0.45 0.11 0.21 4.1 30 <10 <10 420 8 1-2Bal. 0.45 0.11 0.21 4.1 30 <10 <10 420 8 1-3 Bal. 0.45 0.11 0.21 4.1 30<10 <10 440 8 1-4 Bal. 0.68 0.15 0.34 4.5 100 <10 <10 420 8 1-5 Bal.0.68 0.15 0.34 4.5 100 <10 <10 450 8 1-6 Bal. 0.68 0.15 0.34 4.5 100 <10<10 450 8 1-7 Bal. 0.99 0.24 0.49 4.1 40 <10 <10 450 8 1-8 Bal. 0.990.24 0.49 4.1 40 <10 <10 420 8 1-9 Bal. 0.61 0.20 0.30 3.1 100 <10 <10450 8 1-10 Bal. 0.48 0.19 0.20 2.5 50 <10 <10 400 8 1-11 Bal. 0.60 0.050.70 12 30 <10 <10 370 8 1-101 Bal. 0.09 0.03 0.27 3 40 <10 <10 350 81-102 Bal. 0.09 0.03 0.27 3 40 <10 <10 450 8 1-103 Bal. 0.57 0.3 0.4 1.9100 <10 <10 420 8 1-104 Bal. 0.57 0.3 0.4 1.9 100 <10 <10 500 8 1-105Bal. 0.3 0.1 0.15 3.0 10 <10 <10 500 1.5 1-106 Bal. 0.3 0.1 0.1 3.0 30<10 <10 450 1 1-107 Bal. 0.4 0.13 0.35 3.1 60 <10 <10 450 1

(Measurement of Characteristics)

The copper alloy wires manufactured in manufacturing patterns (A) to (C)φ0.35 mm or φ0.16 mm) each had its tensile strength (MPa), elongation atbreak (%), conductivity (% IACS) and work hardening exponent examined. Aresult is shown in Table 3.

The conductivity (% IACS) was measured in a bridge method. The tensilestrength (MPa), the elongation at break (%) and the work hardeningexponent were measured using a general-purpose tensile tester accordingto JIS Z 2241 (a metal material tensile test method, 1998).

Covered electrical wires manufactured in manufacturing patterns (a) to(c) (conductor's cross-sectional area: 0.13 mm²) had their terminalfixing forces (N) examined. In addition, compressed stranded wiresmanufactured in manufacturing patterns (a) to (c) were subjected toexamination for the conductor's impact resistance energy in a state witha terminal attached (J/m, impact resistance E with terminal attached)and the conductor's impact resistance energy (J/m, impact resistance E).A result is shown in Table 3.

Terminal fixing force (N) is measured as follows: At an end of thecovered electrical wire, an insulating covering layer is removed toexpose a conductor that is the compressed stranded wire, and a terminalis attached to one end of the compressed stranded wire. Herein, theterminal is a commercially available crimp terminal and crimped to thecompressed stranded wire. Furthermore, herein, as shown in FIG. 3, anattachment height (a crimp height C/H) was adjusted so that theconductor (or compressed stranded wire) at a terminal attachment portion12 had a transverse cross-sectional area having a value shown in FIG. 3relative to a transverse cross-sectional area of a portion of the mainwire other than the terminal attachment portion (a remaining conductorratio of 70% or 80%).

Using a general-purpose tensile tester, a maximum load (N) for which theterminal did not escape when the terminal was pulled by 100 mm/min wasmeasured. Let this maximum load be a terminal fixing force.

The conductor's impact resistance energy (J/m or (N/m)/m) is measured asfollows: Before an insulating material is extruded, a weight is attachedto a tip of a heat-treated member (i.e., a conductor composed ofcompressed stranded wire), and the weight is lifted upward by 1 m, andthen caused to freely fall. The weight's maximum gravitational weight(kg) for which the conductor does not break is measured, and a productof the gravitational weight, the gravitational acceleration (9.8 m/s²)and the falling distance is divided by the falling distance to obtain avalue (i.e., (weight's gravitational weight×9.8×1)/1), which is definedas the conductor's impact resistance energy.

The conductor's impact resistance energy in a state with a terminalattached (J/m or (N/m)/m) is measured as follows: As has been done inmeasuring a terminal fixing force, as has been described above, beforean insulating material is extruded, a terminal 5 (herein, a crimpterminal) is attached to one end of a conductor 10 of a heat-treatedmember (a conductor composed of a compressed stranded wire) to thusprepare a sample S (herein, having a length of 1 m), and terminal 5 isfixed by a jig J as shown in FIG. 4. A weight W is attached to the otherend of sample S, and is lifted to the position at which terminal 5 isfixed, and then the weight is caused to freely fall. Similarly as donefor the impact resistance energy of the conductor described above, amaximum gravitational weight of weight W for which conductor 10 is notbroken is measured, and ((the weight's gravitational weight×9.8×1)/1) isdefined as an impact resistance energy in a state with the terminalattached.

TABLE 3 composition characteristics mass wire tensile elongation worksample (% by mass) ratio diameter strength at break conductivityhardening No. Cu Fe P Sn Fe/P process (mm) (MPa) (%) (% IACS) exponent1-1 Bal. 0.45 0.11 0.21 4.1 C 0.16 463 13 69 0.146 1-2 Bal. 0.45 0.110.21 4.1 C 0.16 463 13 69 0.146 1-3 Bal. 0.45 0.11 0.21 4.1 C 0.16 41615 70 0.195 1-4 Bal. 0.68 0.15 0.34 4.5 A 0.35 487 8 71 0.110 1-5 Bal.0.68 0.15 0.34 4.5 A 0.35 420 12 72 0.175 1-6 Bal. 0.68 0.15 0.34 4.5 A0.35 420 12 72 0.175 1-7 Bal. 0.99 0.24 0.49 4.1 B 0.16 451 16 66 0.1611-8 Bal. 0.99 0.24 0.49 4.1 B 0.16 560 10 64 0.100 1-9 Bal. 0.61 0.200.30 3.1 B 0.16 480 15 64 0.149 1-10 Bal. 0.48 0.19 0.20 2.5 B 0.16 54610 70 0.122 1-11 Bal. 0.60 0.05 0.70 12 B 0.16 477 12 72 0.141 1-101Bal. 0.09 0.03 0.27 3 C 0.16 499 7 68 0.070 1-102 Bal. 0.09 0.03 0.27 3C 0.16 313 26 77 0.315 1-103 Bal. 0.57 0.3 0.4 1.9 C 0.16 569 11 520.081 1-104 Bal. 0.57 0.3 0.4 1.9 C 0.16 381 22 56 0.230 1-105 Bal. 0.30.1 0.15 3.0 C 0.35 296 20 66 0.231 1-106 Bal. 0.3 0.1 0.1 3.0 C 0.16480 6 79 0.082 1-107 Bal. 0.4 0.13 0.35 3.1 C 0.16 540 4 75 0.061characteristics (0.13 mm²) impact resistance remaining E in stateconductor terminal with terminal impact sample ratio fixing forceattached resistance E No. process (%) (N) (J/m) (J/m) 1-1 c 80 67 5 6.71-2 c 70 63 2 6.7 1-3 c 70 59 4.4 7.7 1-4 a 80 69 2.3 5 1-5 a 80 61 67.3 1-6 a 70 58 2.7 7.3 1-7 b 80 66 6.3 9.2 1-8 b 80 80 1.7 4.6 1-9 b 8061 6.9 11.3 1-10 b 80 77 5.3 10.4 1-11 b 80 60 3.8 7.8 1-101 c 80 69 0.73.9 1-102 c 70 47 9.3 9.7 1-103 c 80 80 1.0 8.5 1-104 c 70 55 6.1 10.11-105 c 80 37 10.5 12.4 1-106 c 80 60 1.3 3.4 1-107 c 80 70 0.6 2.8

As shown in Table 3, it can be seen that sample Nos. 1-1 to 1-11 allhave conductivity, strength and impact resistance in a better balancethan sample Nos. 1-101 to 1-107. Further, sample Nos. 1-1 to 1-11 arealso all excellent in impact resistance in a state with a terminalattached. Quantitatively, they are as follows:

Sample Nos. 1-1 to 1-11 all have tensile strength of 385 MPa or more.Furthermore, these samples all have tensile strength of 400 MPa or more,even 415 MPa or more, and there are also many samples having 420 MPa ormore.

Sample Nos. 1-1 to 1-11 all have conductivity of 60% IACS or more, even62% IACS or more, and there are also many samples having 65% IACS ormore, even 68% IACS or more.

Sample No. 1-1 to 1-11 all have a conductor having impact resistanceenergy of 4 J/m or more, even 4.5 J/m or more, and there are also manysamples having 5 J/m or more, even 6 J/m or more.

Sample No. 1-1 to 1-11 all have a conductor having impact resistanceenergy of 1.5 J/m or more, even 1.7 J/m or more in a state with aterminal attached, and there are also many samples having 2.5 J/m ormore, even 3 J/m or more. Covered electrical wires of sample Nos. 1-1 to1-11 including a conductor as described above are expected to havehigher impact resistance energy in a state with a terminal attached andhigher impact resistance energy of the main wire (see Test Example 2).

Further, sample Nos. 1-1 to 1-11 all have high elongation at break, andit can be seen that the samples have high strength, high toughness andhigh conductivity in a good balance. Quantitatively, there are also manysamples providing elongation at break of 5% or more, even more than 7%,8% or more, and there are also many samples providing 10% or more.Further, sample Nos. 1-1 to 1-11 all present terminal fixing force of 45N or more, even 50 N or more, more than 55 N, and it can be seen thatthey can firmly fix a terminal. In addition, sample Nos. 1-1 to 1-11 allhave a work hardening exponent as large as 0.1 or more, and many samplesthereof have 0.12 or more, even 0.13 or more, and it can be seen thatthey easily obtain a strength enhancement effect through work hardening.

A reason for having been able to obtain the above result is consideredas follows: Sample Nos. 1 to 1-11 are all composed of a copper alloyhaving a specific composition including Fe, P, and Sn in a specificrange as described above, and undergo a heat treatment as appropriate.Accordingly, it is believed that precipitation of Fe and P and solidsolution of Sn were able to be enhanced to provide satisfactorilyeffectively increased strength, and solid solution of P or the like wasable to be reduced based on appropriate precipitation of Fe and P tosatisfactorily effectively maintain high conductivity of Cu.Furthermore, it is believed that the above specific composition andappropriate heat treatment were able to enhance precipitation of Fe andP and prevent coarsening and excessive softening of crystals, and thuswhile high strength of 385 MPa or more was provided, large elongation atbreak and excellent toughness were also provided, and even when animpact was received, breakage was hard to occur, and excellent impactresistance was thus also obtained (for example, see sample Nos. 1-101and 1-102 for comparison). In this test, it can be said that it ispreferable to set the heat treatment temperature at a temperatureselected from a range of 350° C. or higher and less than 500° C., andthe holding time to be longer than 4 hours (for example, see samplesNos. 1-105 to 1-107 for comparison). Furthermore, it can be said that,in this test, in addition to adjusting a heat treatment condition, asdescribed above, a copper alloy having a specific composition, that is,a mass ratio of Fe/P of 4.0 or more, more easily increases conductivityand hence easily has conductivity as high as 60% IACS or more (forexample, see sample Nos. 1-103 and 1-104 for comparison). Note that itis believed that sample Nos. 1-105 to 1-107 more easily became high inconductivity than sample Nos. 1-1 to 1-11 since the former containedadditive elements in a smaller amount than the latter.

Furthermore, herein, it is believed that appropriately containing C, Mnand Si and thereby causing these elements to function as antioxidantsprevented oxidation of Fe, P, and Sn and thus enabled appropriateprecipitation of Fe and P and appropriate solid solution of Sn.Furthermore, it is believed that reduction in conductivity due tocontaining C, Mn and Si was also able to be suppressed. It is believedthat the above result was obtained in this test because a content of Cof 100 ppm by mass or less, a total content of Mn and Si of 20 ppm bymass or less, a total content of these three elements of 150 ppm by massor less, 120 ppm by mass or less in particular, allowed the aboveantioxidation effect and conductivity reduction suppressing effect to beappropriately obtained.

It is believed that one reason for large terminal fixing force is thattensile strength was high strength as high as 385 MPa or more, and inaddition, a work hardening exponent as large as 0.1 or more allowedwork-hardening to provide a strength enhancement effect. For example,Sample Nos. 1-1 and 1-101, which have different work hardening exponentsand identical conditions for attaching a terminal (or the same remainingconductor ratio) will be compared. Although sample No. 1-1 is lower intensile strength than sample No. 1-101, the former has a terminal fixingforce of a level equivalent to that of the latter and in addition,significantly larger impact resistance energy in a state with theterminal attached than the latter. It is believed that sample No. 1-1compensated for the small tensile strength by work hardening.Furthermore, it is believed the conductor had a terminal attachmentportion satisfactorily effectively enhanced in strength throughwork-hardening accompanying compression-working, and was thus alsoexcellent in impact resistance in a state with a terminal attached. Inaddition, in this test, when noting tensile strength and terminal fixingforce, it can be said that there is a correlation such that terminalfixing force increases as tensile strength increases.

This test has indicated that applying plastic-working such aswire-drawing and a heat treatment such as an aging/softening treatmentto a copper alloy having a specific composition including Fe, P and Snin a specific range as described above can provide a copper alloy wireand a copper alloy stranded wire excellently conductive and excellent instrength, and in addition, also excellent in impact resistance, and acovered electrical wire and a terminal-equipped electrical wire usingthe copper alloy wire and the copper alloy stranded wire as a conductor.In addition, it can be seen that even the same composition can be variedin tensile strength, conductivity, impact resistance energy and the likeby adjusting the heat treatment's condition (for example, see comparisonbetween sample No. 1-2 and No. 1-3, comparison between sample No. 1-4and No. 1-5, and comparison between sample No. 1-7 and No. 1-8). Forexample, when the heat treatment's temperature is raised, theconductivity and the conductor's impact resistance energy tend to behigh. In addition, as the Sn content increases, the tensile strengthtends to be higher (for example, see and compare sample Nos. 1-8, 1-4and 1-2).

Test Example 2

Similarly as has been done in test example 1, copper alloy wires ofvarious compositions and covered electrical wires using the obtainedcopper alloy wires as conductors were manufactured under variousmanufacturing conditions and had their characteristics examined.

In this test, a copper alloy wire (a heat-treated member) having a wirediameter of 0.16 mm was produced in manufacturing pattern (B) of TestExample 1. A heat treatment was performed in conditions as shown inTable 4. Furthermore, similarly as has been done in test example 1, theobtained copper alloy wire (having a wire diameter of 0.16 mm) had itsconductivity (% IACS), tensile strength (MPa), elongation at break (%),and work hardening exponent examined. A result thereof is shown in Table4.

Manufacturing pattern (b) of test example 1 was used to prepare awire-drawn member having a wire diameter of 0.16 mm and 7 suchwire-drawn members were twisted together and subsequentlycompression-molded to prepare a compressed stranded wire having atransverse cross sectional area of 0.13 mm² which was in turn subjectedto a heat treatment under the conditions shown in Table 5. The obtainedheat-treated member was surrounded by an insulating material (PVC or PP)extruded to have a thickness shown in Table 5 (0.20 mm or 0.23 mm) tothus form an insulating covering layer to thus manufacture a coveredelectrical wire with the above heat-treated member as a conductor.

The obtained heat-treated member (a conductor composed of a compressedwire member) had its load at break (N), elongation at break (%), andelectric resistance per 1 m (mΩ/m) examined. The obtained coveredelectrical wire had its load at break (N), elongation at break (%), andimpact resistance energy (J/m) of the main wire examined. A resultthereof is shown in table 5.

Load at break (N) and elongation at break (%) were measured using ageneral-purpose tensile tester in conformity to JIS Z 2241 (a metalmaterial tensile test method, 1998). Electrical resistance was measuredin accordance with JASO D 618 and a resistance measuring device of afour terminal method was used to measure a resistance value for a lengthof 1 m. The main wire's impact resistance energy was measured in thesame manner as in Test Example 1, with the covered electrical wire as atarget to be tested.

The obtained covered electrical wire had its impact resistance energy(J/m) measured in a state of with a terminal attached. A result thereofis shown in table 6. In this test, at an end of covered electrical wire3, an insulating covering layer was removed to expose a conductor thatis a compressed stranded wire, and a crimp terminal was attached asterminal 5 to one end of the compressed stranded wire, and measurementwas done in a manner similar to that in test example 1 (see FIG. 4). Asthe crimp terminal was prepared a crimp terminal formed by press-forminga metal plate (made of a copper alloy) into a predetermined shape, andincluding fitting portion 52, wire barrel portion 50, and insulationbarrel portion 54 (an overlapping type) as shown in FIG. 2. Here, avariety of types of crimp terminals composed of metal plates havingthicknesses (mm) shown in Table 6 and having surfaces plated withplating material types shown in Table 6 (tin (Sn) or gold (Au)) wereprepared, and attached to a conductor of a covered electrical wire ofeach sample such that wire barrel portion 50 had an attachment height(C/H (mm)) and insulation barrel portion 54 has an attachment height(V/H (mm)) as shown in Table 6.

TABLE 4 composition heat trace treatment characteristics (φ0.16 mm) masscomponents conditions tensile elongation work sample (% by mass) ratio(ppm by mass) temperature time strength at break conductivity hardeningNo. Cu Fe P Sn Fe/P C Mn Si process (° C.) (h) (MPa) (%) (% IACS)exponent 2-11 Bal. 0.61 0.14 0.31 4.4 40 <10 <10 B 450 8 515 12 63 0.1222-12 Bal. 0.57 0.13 0.31 4.4 40 <10 <10 B 440 8 461 13 65 0.121 2-13Bal. 0.63 0.15 0.26 4.2 40 <10 <10 B 440 8 493 11 65 0.121 2-14 Bal.0.61 0.15 0.14 4.1 40 <10 <10 B 440 8 469 12 71 0.139 2-101 Bal. 0.090.03 0.27 3 40 <10 <10 B 350 8 499 7 68 0.07

TABLE 5 conditions conductor's for heat characteristics electricalelectrical wire's treatment for (0.13 mm²) wire's cover characteristicsconductor load at elongation electrical insulation load at elongationimpact sample temperature time break at break resistance insulatingthickness break at break resistance E No. (° C.) (h) (N) (%) (mΩ/m)cover (mm) (N) (%) (J/m) 2-11 450 8 68 12 201 PVC 0.23 85 14 12.5 2-12440 8 61 13 194 PVC 0.23 81 15 12.6 2-13 440 8 65 11 192 PVC 0.23 82 1311.3 PP 0.20 84 13 11.9 PP 0.23 87 13 12.3 2-14 440 8 62 12 177 PVC 0.2378 14 11.5 2-101 350 8 66 7 184 PVC 0.23 81 9 7.3

TABLE 6 impact resistance energy in state with terminal attached (J/m)condition No. 1 2 3 4 5 6 7 8 9 10 terminal plate thickness (mm)(terminal plating material type) 0.15 0.25 0.25 0.25 0.25 0.2 0.25 0.250.25 0.25 (Sn) (Sn) (Au) (Sn) (Au) (Sn) (Sn) (Sn) (Sn) (Sn) V/H mmcovering material 1.10 1.45 1.45 1.45 1.45 1.00 1.40 1.35 1.30 1.25sample type and crimping C/H mm No. condition 0.61 0.76 0.75 0.75 0.790.64 0.75 0.75 0.75 0.75 2-11 PVC 0.23 mm 3.9 5.4 4.9 4.4 5.4 6.4 4.44.9 4.4 3.9 2-12 PVC 0.23 mm 3.9 6.4 5.4 4.4 5.4 6.4 4.4 — — — 2-13 PVC0.23 mm 3.9 5.4 4.9 4.4 5.4 6.4 4.4 — — — PP 0.20 mm 4.4 5.9 5.4 5.9 5.96.9 4.9 — — — PP 0.23 mm 4.9 6.4 5.9 6.4 6.4 7.4 5.4 — — — 2-14 PVC 0.23mm 3.9 6.4 5.4 4.4 5.4 6.4 4.4 — — — 2-101 PVC 0.23 mm 1.0 2.5 2.0 1.52.5 3.0 1.5 2.0 1.5 1.0

As shown in Tables 4 and 5, it can be seen that sample Nos. 2-11 to 2-14are all excellent in conductivity, strength and impact resistance in agood balance as compared with sample No. 2-101 having the same wirediameter or having a conductor with the same cross sectional area.Further, as shown in FIG. 6, sample Nos. 2-11 to 2-14 are also allexcellent in impact resistance in a state with a terminal attached.Quantitatively, they are as follows:

Sample Nos. 2-11 to 2-14 all have tensile strength of 385 MPa or more.Furthermore, these samples all have tensile strength of 400 MPa or more,even 450 MPa or more (see Table 4).

Sample Nos. 2-11 to 2-14 all have conductivity of 60% IACS or more, even62% IACS or more (see Table 4).

Sample Nos. 2-11 to 2-14 all have the main wire's impact resistanceenergy of 9 J/m or more, even 10 J/m or more (see Table 5).

Sample Nos. 2-11 to 2-14 in a state with a terminal attached all haveimpact resistance energy of 3 J/m or more, even 3.5 J/m or more, 3.8 J/mor more, and there are also many samples having 4 J/m or more (see Table6).

In this test, it can be said that even if C/H and V/H are the same,changing the terminal's plating material type, cover type, coveringthickness and the like may further enhance impact resistance energy inthe state with the terminal attached (for example, compare condition No.2 and condition No. 3 in Table 6). Furthermore, in this test, it can besaid that even when the same crimp terminal is used, changing V/H (inthis case, increasing V/H) tends to further enhance impact resistanceenergy in the state with the terminal attached (for example, compareconditions No. 2, No. 4, No. 7 to No. 10 in Table 6).

Further, as shown in Table 4, sample Nos. 2-11 to 2-14 all have anelongation at break of 5% or more, even 10% or more, and it can be seenthat they have high strength, high toughness and high conductivity in agood balance, similarly as seen in test example 1. Further, as shown inTable 5, it can be said that a compressed stranded wire is larger intensile strength (load at break/cross sectional area) than a solid wire(see conductor's characteristics) and furthermore, it can be said that acovered electrical wire having an insulating covering layer can enhancetensile strength more than a compressed stranded wire (see electricalwire's characteristics). It can be said that even a compressed strandedwire can maintain a solid wire's elongation at break (seecharacteristics in Table 4 and conductor's characteristics in Table 5and compare them) and it can be said that a covered electrical wireincluding an insulating covering layer can improve elongation at breakmore than the compressed stranded wire (see the table 5 conductor'scharacteristics and electrical wire's characteristics and compare them).It can be said that the covered electrical wire including the insulatingcovering layer tends to have higher impact resistance energy in a statewith a terminal attached and higher impact resistance energy of the mainwire than a case with a conductor alone as shown in test example 1.

In addition, sample Nos. 2-11 to 2-14 all have a work hardening exponentof 0.1 or more, even 0.12 or more. It is believed that such sample Nos.2-11 to No. 2-14 can all fix a terminal firmly, and are excellent inimpact resistance in a state with the terminal attached and in addition,also excellently fix the terminal.

One reason for having been able to obtain the above result is consideredas follows: similarly as in test example 1, comprising a copper alloyhaving a specific composition including Fe, P and Sn in a specificrange, and performing an appropriate heat treatment, were able toenhance precipitation of Fe and P and solid solution of Sn to providesatisfactorily effectively increased strength, and were able to reducesolid solution of P or the like to satisfactorily effectively maintainhigh conductivity of Cu. Furthermore, it is believed that, by anappropriate heat treatment, excellent toughness was also provided whiletensile strength is high strength as high as 385 MPa, and excellentimpact resistance and excellent impact resistance in a state with aterminal attached were thus also provided. In particular, as well as intest example 1, it is believed that appropriately containing C, Mn andSi effectively prevented oxidation of Fe, P, Sn and containing C or alike deoxidant element effectively suppressed reduction in conductivity.

The present invention is defined by the terms of the claims, rather thanthe examples described above, and is intended to include anymodifications within the meaning and scope equivalent to the terms ofthe claims.

For example, the copper alloy's composition, the copper alloy wire'swire diameter, how many wires are twisted together, and a heat treatmentcondition in Test Examples 1 and 2 can be changed as appropriate.

[Additional Notes]

As a covered electrical wire, a terminal-equipped electrical wire, acopper alloy wire, and a copper alloy stranded wire which areexcellently conductive and excellent in strength, and in addition, alsoexcellent in impact resistance, the following configuration can be made.The following configuration has Fe/P within a specific range, andaccordingly, helps to form a compound without excess or deficiency of Feand P, as described above, and as a result, enhanced precipitation caneffectively enhance strength more appropriately, and excessive solidsolution of P can be reduced to effectively maintain the matrix phase'shigh conductivity, as appropriate.

[Additional Note 1]

A covered electrical wire comprising a conductor and an insulatingcovering layer provided outside the conductor,

-   -   the conductor being a stranded wire composed of a strand of a        plurality of copper alloy wires:    -   composed of a copper alloy containing        -   Fe in an amount of 0.1% by mass or more and 1.6% by mass or            less,        -   P in an amount of 0.05% by mass or more and 0.7% by mass or            less, and        -   Sn in an amount of 0.05% by mass or more and 0.7% by mass or            less,        -   with the balance being Cu and impurities, and        -   having a mass ratio of Fe/P of 4.0 or more; and    -   having a wire diameter of 0.5 mm or less.

[Additional Note 2]

A terminal-equipped electrical wire comprising a covered electrical wireindicated in [additional note 1] and a terminal attached to an end ofthe covered electrical wire.

[Additional Note 3]

A copper alloy wire used for a conductor, the copper alloy wire:

-   -   being composed of a copper alloy containing        -   Fe in an amount of 0.1% by mass or more and 1.6% by mass or            less,        -   P in an amount of 0.05% by mass or more and 0.4% by mass or            less, and        -   Sn in an amount of 0.05% by mass or more and 0.7% by mass or            less,        -   with the balance being Cu and impurities, and        -   having a mass ratio of Fe/P of 4.0 or more; and    -   having a wire diameter of 0.5 mm or less.

[Additional Note 4]

A copper alloy stranded wire formed of a strand of a plurality of copperalloy wires each indicated in [additional note 3].

REFERENCE SIGNS LIST

-   -   1 copper alloy wire,        -   10 copper alloy stranded wire (conductor),        -   12 terminal attachment portion,    -   2 insulating coating layer,    -   3 covered electrical wire,    -   4 terminal-equipped electrical wire,    -   5 terminal,        -   50 wire barrel portion,        -   52 fitting portion,        -   54 insulation barrel portion,    -   S sample,    -   J jig,    -   W weight

The invention claimed is:
 1. A covered electrical wire comprising aconductor and an insulating covering layer provided outside theconductor, the conductor being a stranded wire composed of a strand of aplurality of copper alloy wires: composed of a copper alloy consistingof Fe in an amount of 0.1% by mass or more and 1.6% by mass or less, Pin an amount of 0.05% by mass or more and 0.7% by mass or less, Sn in anamount of 0.05% by mass or more and 0.7% by mass or less, and C, Si, andMn in an amount of more than 30 ppm and less than 70 ppm by mass intotal and C is contained in an amount of 30 ppm or more, with thebalance being Cu and impurities, and each copper alloy wire having awire diameter of 0.5 mm or less, the copper alloy wire having a tensilestrength of 385 MPa or more and a work-hardening exponent of 0.1 ormore, wherein the copper alloy has a mass ratio of Fe/P of 4.0 or more.2. The covered electrical wire according to claim 1, wherein the copperalloy wire provides an elongation at break of 5% or more.
 3. The coveredelectrical wire according to claim 1, wherein the copper alloy wire hasa conductivity of 60% IACS or more and a tensile strength of 400 MPa ormore.
 4. The covered electrical wire according to claim 1, having aterminal fixing force of 45 N or more.
 5. The covered electrical wireaccording to claim 1, having an impact resistance energy of 3 J/m ormore in a state with a terminal attached.
 6. The covered electrical wireaccording to claim 1, wherein an impact resistance energy of the coveredelectrical wire is 6 J/m or more.
 7. A terminal-equipped electrical wirecomprising a covered electrical wire according to claim 1 and a terminalattached to an end of the covered electrical wire.